- Development Gag: Umiko the ninja pirate, who is written as a part of Grave Humor in this game, was originally supposed to be a companion for Molly the Were-Zompire from the interactive novel of the same name.
- DVD Commentary: Starting a New Game+ will give you the option to turn the developer commentary on or off. The commentaries come in the form of question marks that are scattered throughout the game.
- What Could Have Been: The developer commentary and design document reveal many things that were changed, removed or never implemented.
- As noted on the main page, the Three Heroes of Goodly Justice (fought as the first boss fight) were going to be a recurring element...but the developers forgot about them. As a result, they only reappear in Very Definitely Final Dungeon, exactly as strong as before.
- At the start of the game, Cthulhu was supposed to be controlled at the start of the game in full power, fighting a group of heroes before the main premise of the game would be kickstarted. It was removed because the trial version had only 8 minutes of play, and the players would not be able to get to the point of the game immediately.
- Some characters were supposed to be played differently than how they are currently. Sharpe was supposed to "evolve" as he gains new "equipment" via levelling up, but in the final game he has blades and hilts as equipment (however, the idea of evolving equipment was reused for Dark Umi). Paws was supposed to switch between mage/warrior class type depending on Sanity Meter (described below). Ember was supposed to have breath mints as equipment, but in the final game he cannot change equipment at all.
- Two characters were supposed to have different personalities. October was supposed to be much more pessimistic than in the final game, while Dacre was supposed to be Only Sane Man who would try to convince others to do the right thing but lacking the charisma to do so.
- Earlier, the game had much more emphasis on Cthulhu trying to undo the curse in different ways (e.g. trying to use Sharpe's power, alien technologies and healing water from shrine), but eventually the game had set on Cthulhu trying to become a true hero and attempting to get enough hero points to break his curse.
- Cthulhu was supposed to start at level 5 in enclosed world map area, going only through beach cliff. In the final game, Cthulhu starts at level 3 and in the beach cliff dungeon itself, rather than near it.
- The design document reveals that insanity system was much different. Instead of being non-standard status effect, there was supposed to be Sanity Meter for enemies and characters, which would turn them insane when it reaches zero.
- Miskatonia was originally supposed to be named Arkham, but the developers ended up going against using this name, considering it's used in other works.
- The townsfolk was supposed to be hostile to Cthulhu until Sharpe would be unlocked as a party member.
- Shrine of Heroes was supposed to have traps, but at the end there was only lever/door puzzle.
- The towns' pubs were originally going to contain a Dating Sim minigame between Cthulhu and Umi, but time constraints forced this to be scrapped.
- Also, for each optional dungeon there were planned to be sidequests, but time constraints meant that only the first one got a sidequest, and the rest were purely optional treasure hunts similar to those in Breath of Death VII. The Swamp of Despair, in particular, has a Dummied Out overworld sprite for Fire Whale, the boss of location, indicating this sidequest was so close to making it into the game.
- Dunwitch (under the working name Zombie City) was supposed to resemble a modern city, but it was changed to steampunk to avoid the clashing style. Also, zombies were supposed to disappear, but due to how hard it would be to make a new zombie-less version of the map, the zombies instead underwent a HeelRace Turn.
- Cthulhu was supposed to find out about Alien Invasion during the Dunwitch chapter, but instead he learns of it only when visiting Providence.
- One pre-release screenshot shows that Shoggoth was supposed to be fought in a swamp level, presumably as a random mini-boss-esque encounter. In the final game, Shoggoth became a boss of Water Shrine instead.
- The volcano was supposed to start at summit and going down to the core, but it was changed for the sake of Shout-Out to Dragon Quest III intro with fighting the dragon at the summit of the volcano (as well as because it was easier to make entrance at the bottom than at the top).
- At first, the ending where Cthulhu destroys the world and the ending where Cthulhu embraces his heroism and saves the world were separate. But they decided to have an evil ending start and later get rewritten into good ending for the sake of the Rule of Funny.
- Speaking of the ending, the original end of the game was much more different. At first it was supposed to be found out that Cthulhu's cult was behind everything bad happening in the gamenote , and then they break the curse on Cthulhu and the result splits him in two Cthulhus: one is evil, and the other is heroic. The evil Cthulhu would then end up being the Final Boss of the gamenote . The final dungeons were supposed to be Cult Headquartersnote and Cthulhu's Watery Temple, which is made of tentaclesnote .
- Bonus campaign was supposed to be merely a remake of the original campaign, but with different monster setups, different chests and Molly the Were-Zompire being a part of the cast. Eventually, it was changed and dubbed Cthulhu's Angels, starring October as the main character and featuring Elonalina, Dark Umi and Molly as party members, and bosses were the ones who went through changes.
Trivia / Cthulhu Saves the World